1 files changed, 50 insertions, 0 deletions
diff --git a/moonphase.py b/moonphase.py
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+++ b/moonphase.py
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+#!/usr/bin/env python
+"""
+moonphase.py - Calculate Lunar Phase
+Author: Sean B. Palmer, inamidst.com
+Cf. http://en.wikipedia.org/wiki/Lunar_phase#Lunar_phase_calculation
+"""
+
+import math
+import decimal
+import datetime
+
+dec = decimal.Decimal
+
+
+def position(now=None):
+    if now is None:
+        now = datetime.datetime.now()
+
+    diff = now - datetime.datetime(2001, 1, 1)
+    days = dec(diff.days) + (dec(diff.seconds) / dec(86400))
+    lunations = dec("0.20439731") + (days * dec("0.03386319269"))
+
+    return lunations % dec(1)
+
+
+def phase(pos):
+    index = (pos * dec(8)) + dec("0.5")
+    index = math.floor(index)
+    return {
+       0: "New Moon",
+       1: "Waxing Crescent",
+       2: "First Quarter",
+       3: "Waxing Gibbous",
+       4: "Full Moon",
+       5: "Waning Gibbous",
+       6: "Last Quarter",
+       7: "Waning Crescent"
+    }[int(index) & 7]
+
+
+def main():
+    pos = position()
+    phasename = phase(pos)
+
+    roundedpos = round(float(pos), 3)
+    num_days = float(roundedpos * 29.6)
+    print("%s (%s) %s days" % (phasename, roundedpos, num_days))
+
+if __name__=="__main__":
+    main()